“What was carried out by G4S staff on Facebook is an appalling breach of trust. Their stated role is not just to provide security, it also relates to the welfare of asylum seekers in their care,” he said.

“I understand the government has responded and condemned what has happened and I hope that some appropriate action is taken.”

The immigration minister, Scott Morrison, has provided an update on the wellbeing of the man. A spokeswoman for Morrison said: “This person received appropriate medical attention at the time and remains at the Manus Island OPC.”

Greens senator Sarah Hanson-Young said guards who thought self-harm was a joke should not be in supervisory roles.

“What this really does is just highlight how toxic the culture is within the detention camp,” she told ABC radio.

Following the revelations, the Royal Australasian College of Physicians president, Leslie Bolitho, called on the federal government to be more open about healthcare for asylum seekers on Manus Island and establish an independent oversight system.

“The government must be open and transparent about the processes it has in place to protect the health of vulnerable adults and children in immigration detention facilities, and in particular the ongoing medical treatment and welfare of this individual.

“This can be achieved by establishing an independent mechanism for the oversight and management of healthcare services available in offshore detention facilities and regional processing centres.”

He said the RACP remained concerned about the level of care provided to asylum seekers.

“There is a large body of evidence to suggest that prolonged detention, particularly in isolated locations with poor access to health and social services, combined with an uncertainty as to the outcome of asylum seeker claims, has severe and detrimental effects on the health of individuals,” he said.

The immigration department’s former communications manager, Sandi Logan, also tweeted about the incident and described it as “indefensible”.

“Imagine those trying to explain, defend such callous disregard, esp given the circumstances,” he tweeted.

Hanson-Young said the brutality and chaos on the Manus Island facility needed to be addressed.

“The Coalition government has quadrupled the number of people in these horrific conditions since these incidents were logged and I hold grave fears for those who are currently locked up there,” she said.

“The previous government repeatedly lied and told the Australian people that conditions on Manus Island were acceptable for refugees, including children. This government is combining similar lies with sinister secrecy and it is the refugees who are suffering as a result.”